Hampton Bay fan cap

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Old 08-14-14, 08:34 AM
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Hampton Bay fan cap

OK - I have don a bit of research on just this subject due to a blown fan capacitor on an old Hampton Bay. HB is not so good at getting replacement old parts, so thus begun the process of trying to source the replacement capacitor elsewhere. Finding a CBB61 that is an exact match is near impossible, but I learned that voltage ratings on them is not the major concern as long as it is at least double the incoming. (120V should rate 250+V) The microfarad (uF) rating is what is key. They should match to make the fan work the same.

So, getting to this thread; my assumption is my capacitor had failed due to "under-powering" it. How? A standard light dimmer or cheap fan dimmer is a rheostat dimmer. They basically reduce the voltage being supplied to the light/fan. Lights (incandescent/LED) can use reduced input, whereas a motor should not. Thus the capacitor inside the fan. The reduced power over a period of time caused the capacitor to fail due to "assumed" over heating.

So, no I am replacing the capacitor and removing the dimmer. If you have a capacitor type dimmer, it will always send 120V to the fan, but at a different amount. The existing capacitor will be safe.

Alternatively (I have not tried this yet), one could assume that when using a capacitor dimmer, the fan capacitor is no longer needed. One could connect the incoming power to to fan power directly (bypassing the fan mounted speed switch). The dimmer would replace the fan capacitor and provide the necessary resistance for speed control. The problem may be trying to find one that uses the same resistance ratings.

Thoughts?
 
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Old 08-14-14, 03:46 PM
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Welcome to the forums!

I have moved your post to its own thread. It is always better to start your own thread so then your question will get the attention it deserves.
 
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Old 08-14-14, 04:58 PM
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Welcome to the forums.


A standard light dimmer or cheap fan dimmer is a rheostat dimmer.
Incorrect. A standard dimmer uses a variable resistor to control a silicon controlled rectifier or some other type of inexpensive switching semi conductor.


Some ceiling fans use a capacitor to start and a second one to run. An AC motor needs a rotating magnetic field in order turn the motor shaft. The 120v is sent to different caps and different windings to supply a locally generated "second phase."

one could assume that when using a capacitor dimmer, the fan capacitor is no longer needed
Also incorrect.

The best speed control.... not dimmer..... to use for a fan utilizes PWM (pulse width modulation). This type of control is extremely efficient, good for the motor and generates very little heat. They are a little pricey but worth it.

So I would recommend replacing the capacitor in your fan. If you need help sourcing the part.... post the specs. for me.
 
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Old 08-15-14, 08:32 AM
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Thanks for the reply and corrections. However, can I assume the cheap dimmer was still my downfall due to reduced voltage?

Can I also assume that if I were to get a PWM, I could bypass the speed control switch and directly connect the power source to the fan motor? Currently, I have a single incoming wire from the power source feeding my capacitor and three legs connecting to the speed control switch and a single leg leaving to the motor.
 
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Old 08-15-14, 11:44 PM
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No.... you still need a capacitor in the fan to supply a second out of phase magnetic field.
 
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